This invention relates to conveying systems and more specifically to monorail systems or overhead operation, i.e. with suspended cars, cabins, or the like load receiving arrangements. The invention is particulary related to roller coaster type arrangements, i.e. where a car is caused to move along a rail-bound path arranged as a closed loop with more or less inclined portions and a series of curves, i.e. for amusement purposes in fairs, amusement parks and the like.
Monorail systems with suspended vehicles for moving persons or goods are known in the art. Normally, such systems are constructed so as to avoid steep passages, i.e. they lack substantial inclinations against the horizontal. To prevent lateral pivoting or swinging of the vehicles or cars one tends to avoid curves, notably narrow curves and lateral guide rails must be provided at the stops or loading stations so as to retain the cars from lateral movements, i.e. swinging.
For amusement purposes, such as in fairs or amusement parks, monorail systems with suspended cars or cabins have been suggested. Such systems have a rail type element arranged in a closed loop and in the manner of roller coasters, i.e. comprising portions with a steep inclination and/or with narrow curves.
German Pat. No. 80,980 teaches cabins having rollers rigidly mounted at the roof of the cabins. The rollers are suspended on a rail helically arranged around a tower so that the cabins will move downwardly around the tower. Accordingly, the cabins are free to swing in any plane, i.e. in planes substantially parallel to the rail, in planes substantially vertical to the rail and in any plane intermediate between the vertical and the parallel planes.
Another prior art rail-bound system of the type in question is disclosed in German Pat. No. 367,410 and comprises a rail having an inverted T-shaped cross-section. A roller gear is rigidly connected to each car and comprises two adjacent support rollers. One roller each is support by one side of the laterally extending component of the rail, i.e. one of the lateral arms of the inverted T-profile of the rail. This arrangement is intended to prevent lateral swinging movement or pivoting of the car while permitting longitudinal swinging, i.e. pivoting in the plane which is parallel to the direction of travel.
French Pat. No. 1,167,272 discloses a further conveying system for amusement purposes and includes cars in rigid connection with a roller gear. The roller gear comprises at least one support roller and lateral guide rollers to provide for a substantially rigid guidance of the moving car or vehicle, i.e. to prevent any swinging or pivoting at all.
When a body is moved through a curve, the centrifugal force will increase as the curve radius decreases and as the speed increases. In monorail systems with susppended cars or cabins the centrifugal forces will cause a freely suspended (i.e. not prevented to swing in any plane) vehicle or car to swing or pivot from its "normal position," i.e. where it is in a position substantially perpendicular below the rail, into an inclined or tilted position. Since the rails or a roller coaster type arrangement for amusement purposes will generally include intermediate straight path portions as well as curved path portions, the full centrifugal forces will act upon the vehicle or car as soon as it enters a curve. As a consequence, a car in such a curve will not only swing into a position corresponding to the resultant of gravitational and centrifugal forces but will first tend to overswing, i.e. swing beyond the position of said resultant, and swing back thereafter. Such pendulum type movement may be quite dangerous because it is slow if compared with the normal travel speed of the car and since, accordingly, it is guite possible that the car after overswinging in a first curve will continue to swing beyond its normal position when entering the next curve. This may cause rather extreme stresses in the car and its suspension and would require extremely strong and very expensive rail structures to prevent structural breakage and still endanger the passenger or passengers.
The lack of acceptance of monorail systems with suspended cars for roller coaster type installations for amusement parks, fairs or the like is probably due to these disadvantages. In theory, overswinging of the car due to centrifugal forces can be avoided if circular curves are replaced by so-called clothoidal curves (Cornu-curves). In practice, however, it is not feasible because it would require a very complicated rail or track structure. Also, it would require much more space than normally available for roller coaster installations.